// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_
#define MEDIA_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_

#include <stdint.h>

#include <map>
#include <memory>
#include <set>

#include "base/macros.h"
#include "base/synchronization/lock.h"
#include "base/threading/thread_checker.h"
#include "media/audio/audio_io.h"
#include "media/audio/fake_audio_worker.h"
#include "media/base/audio_converter.h"
#include "media/base/audio_parameters.h"

namespace base {
class SingleThreadTaskRunner;
}

namespace media {

class LoopbackAudioConverter;

// VirtualAudioInputStream converts and mixes audio from attached
// VirtualAudioOutputStreams into a single stream. It will continuously render
// audio until this VirtualAudioInputStream is stopped and closed.
class MEDIA_EXPORT VirtualAudioInputStream : public AudioInputStream {
public:
    // Callback invoked just after VirtualAudioInputStream is closed.
    typedef base::Callback<void(VirtualAudioInputStream* vais)>
        AfterCloseCallback;

    // Construct a target for audio loopback which mixes multiple data streams
    // into a single stream having the given |params|.  |worker_task_runner| is
    // the task runner on which AudioInputCallback methods are called and may or
    // may not be the single thread that invokes the AudioInputStream methods.
    VirtualAudioInputStream(
        const AudioParameters& params,
        const scoped_refptr<base::SingleThreadTaskRunner>& worker_task_runner,
        const AfterCloseCallback& after_close_cb);

    ~VirtualAudioInputStream() override;

    // AudioInputStream:
    bool Open() override;
    void Start(AudioInputCallback* callback) override;
    void Stop() override;
    void Close() override;
    double GetMaxVolume() override;
    void SetVolume(double volume) override;
    double GetVolume() override;
    bool SetAutomaticGainControl(bool enabled) override;
    bool GetAutomaticGainControl() override;
    bool IsMuted() override;

    // Attaches an AudioConverter::InputCallback to be used as input. This
    // VirtualAudioInputStream must outlive all attached streams, so any attached
    // stream must be closed (which causes a detach) before
    // VirtualAudioInputStream is destroyed.
    virtual void AddInputProvider(AudioConverter::InputCallback* input,
        const AudioParameters& params);

    // Detaches an AudioConverter::InputCallback and removes it as input.
    virtual void RemoveInputProvider(AudioConverter::InputCallback* input,
        const AudioParameters& params);

private:
    friend class VirtualAudioInputStreamTest;

    typedef std::map<AudioParameters, LoopbackAudioConverter*> AudioConvertersMap;

    // Pulls audio data from all attached VirtualAudioOutputStreams, mixes and
    // converts the streams into one, and pushes the result to |callback_|.
    // Invoked on the worker thread.
    void PumpAudio();

    const scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner_;

    AfterCloseCallback after_close_cb_;

    AudioInputCallback* callback_;

    // Non-const for testing.
    AudioParameters params_;

    // Guards concurrent access to the converter network: converters_, mixer_, and
    // num_attached_output_streams_.
    base::Lock converter_network_lock_;

    // AudioConverters associated with the attached VirtualAudioOutputStreams,
    // partitioned by common AudioParameters.
    AudioConvertersMap converters_;

    // AudioConverter that takes all the audio converters and mixes them into one
    // final audio stream.
    AudioConverter mixer_;

    // Number of currently attached VirtualAudioOutputStreams.
    int num_attached_output_streams_;

    // Handles callback timing for consumption of audio data.
    FakeAudioWorker fake_worker_;

    std::unique_ptr<AudioBus> audio_bus_;

    base::ThreadChecker thread_checker_;

    DISALLOW_COPY_AND_ASSIGN(VirtualAudioInputStream);
};

} // namespace media

#endif // MEDIA_AUDIO_VIRTUAL_AUDIO_INPUT_STREAM_H_
